This invention relates to a method of producing ferrotitanium alloy from sponge titanium.
The problems of making titanium alloys are well known. These problems arise from the strong tendency of titanium to oxidize and to react with most crucible materials.
A number of techniques have been developed for producing titanium alloy and, in particular, iron titanium alloy, with these techniques experiencing varying degrees of success at varying degrees of cost and complexity. One of the more common techniques is the so-called consumable electrode arc melting method in which powdered iron or steel and titanium are compressed into an electrode and then melted in an electric arc furnace. Although a fairly contaminant free (oxygen free) iron titanium alloy can be obtained using this technique, the production costs are high because of the high cost of electric arc furnaces and the need for first making an electrode of compressed iron or steel and titanium.
A number of other methods have also been suggested for making titanium alloys including those disclosed in U.S. Pat. Nos. 3,410,679 and 3,063,831. In the latter mentioned patent, a process is disclosed in which a charge of titanium scrap (turnings and plate stampings) is placed in a mold or ladle and molten metal is poured onto the scrap. With this method, it is claimed that ferrotitanium containing about 10 to 30% titanium can be obtained. One problem with this process, and possibly the reason for the relative low percentage of titanium which can be obtained in the alloy, is that charges of scrap titanium are quite vacuous, i.e., filled with voids, and so when molten metal is poured onto a charge, the metal has a tendency to flow quickly through the charge to the bottom of the container. As a result, only a portion of the charge is melted, this being that portion directly in the flow path of the molten metal. To insure more complete melting of the charge, the amount of the charge may simply be reduced so that when the molten metal is poured thereover, it covers the entire charge. But, of course, since the amount of titanium must be reduced to achieve this, the resulting alloy contains low percentages of titanium.